In recent years, it is pointed out that the occurrence frequency of arteriosclerosis and various diseases of coronary and encephalic arteries caused thereby is increasing due to increase of the rate of persons of advanced ages, changes of diet, etc. Various factors are considered for occurrence of this arteriosclerosis, and particularly, the increase of cholesterol in the blood is one of the most principal dangerous factors, and agents lowering cholesterol in the blood are effective for prophylaxis and treatment of arteriosclerosis [Agents Used to Treat Hyperlipidemia, Drug Evaluations 6th. edition, 903-926, (1986)]. Further, among these agents lowering cholesterol in the blood, agents inhibiting biosynthesis of cholesterol in the living body are highly rated because of their clear action mechanism and strong medicinal virtues [Proc. Natl. Acad. Sci., 77, 3957 (1980)]. However, since most of cholesterol biosynthesis-inhibiting agents so far known are inhibitors acting at the early stage or the late stage of the biosynthetic pathway, they have problems, for example, that they inhibit formation of other various physiologically important biological products simultaneously when they inhibit cholesterol biosynthesis, and further that accumulation of the precursors formed by the inhibition becomes a cause of other diseases.
The present inventors previously reported that a series of substituted alkylamine derivatives selectively inhibits squalene epoxidase located at the middle stage of the cholesterol biosynthesis system of mammals, and as a result are useful as an agent lowering cholesterol in the blood which has a mode of action different from that of known cholesterol biosynthesis-inhibiting agents (see Japanese Laid-Open Patent Publication No. 193746/1991, EP 0318860A2, WO 90/5132 and EP 0448078A2). Although several reports were made lately, besides the reports of the present inventors, on agents inhibiting squalene epoxidases of mammals, any of the disclosed compounds has only a low activity, and particularly, it is almost impossible to expect their effects on human beings, dogs, etc. [J. Chem. Research (s), 18-19 (1988); J. Am. Chem. Soc., 111, 1508-1510 (1989); ibid., 114, 360-361 (1992); J. Med. Chem., 32, 2152-2158 (1989); Japanese Laid-Open Patent Publication No. 3144/1989].